The earthquake took place in the vicinity of the Cascadia subduction zone where the Juan de Fuca Plate and the Explorer Plate are being subducted under the North American Plate at a rate of 4 centimeters (1.6 in) and less than 2 centimeters (0.79 in) per year respectively, but the event was a crustal intraplate earthquake and was produced from the complicated interaction between the plates in the area. The source of the earthquake was the Nootka transform fault, which separates the Juan de Fuca and Explorer plates and has been the origin of at least five additional moderate to large events since 1918.[3]

1.
Coordinated Universal Time
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Coordinated Universal Time, abbreviated to UTC, is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean time at 0° longitude. It is one of closely related successors to Greenwich Mean Time. For most purposes, UTC is considered interchangeable with GMT, the first Coordinated Universal Time was informally adopted on 1 January 1960. This change also adopted leap seconds to simplify future adjustments, a number of proposals have been made to replace UTC with a new system that would eliminate leap seconds, but no consensus has yet been reached. Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of universal time, see the Current number of leap seconds section for the number of leap seconds inserted to date. The official abbreviation for Coordinated Universal Time is UTC and this abbreviation arose from a desire by the International Telecommunication Union and the International Astronomical Union to use the same abbreviation in all languages. English speakers originally proposed CUT, while French speakers proposed TUC, the compromise that emerged was UTC, which conforms to the pattern for the abbreviations of the variants of Universal Time. Time zones around the world are expressed using positive or negative offsets from UTC, the westernmost time zone uses UTC−12, being twelve hours behind UTC, the easternmost time zone, theoretically, uses UTC+12, being twelve hours ahead of UTC. In 1995, the nation of Kiribati moved those of its atolls in the Line Islands from UTC-10 to UTC+14 so that the country would all be on the same day. UTC is used in internet and World Wide Web standards. The Network Time Protocol, designed to synchronise the clocks of computers over the internet, computer servers, online services and other entities that rely on having a universally accepted time use UTC as it is more specific than GMT. If only limited precision is needed, clients can obtain the current UTC from a number of official internet UTC servers, for sub-microsecond precision, clients can obtain the time from satellite signals. UTC is also the standard used in aviation, e. g. for flight plans. Weather forecasts and maps all use UTC to avoid confusion about time zones, the International Space Station also uses UTC as a time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many time zones, UTC is also used in digital tachographs used on large goods vehicles under EU and AETR rules. UTC divides time into days, hours, minutes and seconds, days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes, the number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead

2.
International Seismological Centre
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1900–1912 J. Milne 1912–1917 H. H. Turner 1918–1931 H. H. Turner 1931–1939 H. Plaskett 1939–1952 Sir Harold Jeffreys 1952–1960 R. Stoneley 1960–1963 P. L. Willmore 1964–1970 P. L. Willmore 1970–1977 E. P. Willeman 2004–2007 A. Shapira 2008–present D. A. Storchak The main scientific goal of the Centre is the compilation of earthquake information. Since 1957 the manipulation of the volume of data has been mainly carried out by computer. Up until then ISS locations were determined manually with the help of a large globe, the ISC now uses a network of workstations accessing a relational database of nearly 50 Gbytes of online data. The analysis of the data is undertaken in monthly batches. During analysis the computer program first groups origin estimates from different agencies, in a typical month more than 200,000 station readings are analysed leading to an average of 10,000 events per month being identified, of which some 4,000 require manual review. Misassociations and other discrepancies are rectified and the remaining unassociated readings are searched for new events, the total number of events listed each month is several times greater than those obtained by any other worldwide location service and results from ISCs goal to provide a fully comprehensive list. This global instrumental earthquake catalogue, covering events for the period 1900–2009, was released in 2013 by the International Seismological Centre, the catalogue was prepared at the request of the GEM Foundation. Epicentral locations and hypocentral depths were recalculated from original travel time using a consistent velocity model. Sources Official website International Seismological Centre Bulletin – IRIS Consortium

3.
Pacific Time Zone
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The Pacific Time Zone observes standard time by subtracting eight hours from Coordinated Universal Time. During daylight saving time, its time offset is UTC−7 and is based on the mean solar time of the 105th meridian west of the Greenwich Observatory. In the United States and Canada, this zone is generically called the Pacific Time Zone. Specifically, it uses Pacific Standard Time when observing standard time, most of Canada uses daylight saving time. In Mexico, the UTC−8 time zone is known as the Northwest Zone, the largest city in the Pacific Time Zone is Los Angeles, the citys metropolitan area is the largest in the zone. The following states or areas are part of the Pacific Time Zone, California Washington Oregon – all, except for most of Malheur County, nevada Idaho Panhandle – the northern half of Idaho, north of the Salmon River. The town of Hyder, Alaska, is officially in the Alaska Time Zone, however, most of the town observes the Pacific Time because of strong connections with nearby Stewart, British Columbia, which is in the Pacific Time Zone. The United States Post Office in Hyder strictly adheres to Alaska Time, in Canada, the Pacific Time Zone includes most of British Columbia, all of Yukon, and the townsite of Tungsten. In Mexico, the state of Baja California lies completely within the Pacific Time Zone and this does not include the state of Baja California Sur, which is south of Baja California. Through 2006, the time changed to daylight time at 02,00 LST to 03,00 LDT on the first Sunday in April. The Canadian provinces and territories that use daylight time each adopted these dates between October 2005 and February 2007, in Mexico, beginning in 2010, the portion of the country in this time zone uses the extended dates, as do some other parts. The vast majority of Mexico, however, still uses the old dates

4.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation

5.
Fault (geology)
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In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is also the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can also release instantaneously when the rate is too great. The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults

6.
British Columbia
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British Columbia is the westernmost province of Canada, with a population of more than four million people located between the Pacific Ocean and the Rocky Mountains. British Columbia is also a component of the Pacific Northwest and the Cascadia bioregion, along with the U. S. states of Idaho, Oregon, Washington and Alaska. The first British settlement in the area was Fort Victoria, established in 1843, subsequently, on the mainland, the Colony of British Columbia was founded by Richard Clement Moody and the Royal Engineers, Columbia Detachment, in response to the Fraser Canyon Gold Rush. Port Moody is named after him, in 1866, Vancouver Island became part of the colony of British Columbia, and Victoria became the united colonys capital. In 1871, British Columbia became the province of Canada. Its Latin motto is Splendor sine occasu, the capital of British Columbia remains Victoria, the fifteenth-largest metropolitan region in Canada, named for the Queen who created the original European colonies. The largest city is Vancouver, the third-largest metropolitan area in Canada, the largest in Western Canada, in October 2013, British Columbia had an estimated population of 4,606,371. British Columbia evolved from British possessions that were established in what is now British Columbia by 1871, First Nations, the original inhabitants of the land, have a history of at least 10,000 years in the area. Today there are few treaties and the question of Aboriginal Title, notably, the Tsilhqotin Nation has established Aboriginal title to a portion of their territory, as a result of the recent Supreme Court of Canada decision. BCs economy is diverse, with service producing industries accounting for the largest portion of the provinces GDP and it is the endpoint of transcontinental railways, and the site of major Pacific ports that enable international trade. Though less than 5% of its vast 944,735 km2 land is arable and its climate encourages outdoor recreation and tourism, though its economic mainstay has long been resource extraction, principally logging, farming, and mining. Vancouver, the provinces largest city and metropolitan area, also serves as the headquarters of many western-based natural resource companies and it also benefits from a strong housing market and a per capita income well above the national average. The Northern Interior region has a climate with very cold winters. The climate of Vancouver is by far the mildest winter climate of the major Canadian cities, the provinces name was chosen by Queen Victoria, when the Colony of British Columbia, i. e. the Mainland, became a British colony in 1858. The current southern border of British Columbia was established by the 1846 Oregon Treaty, British Columbias land area is 944,735 square kilometres. British Columbias rugged coastline stretches for more than 27,000 kilometres and it is the only province in Canada that borders the Pacific Ocean. British Columbias capital is Victoria, located at the tip of Vancouver Island. Only a narrow strip of the Island, from Campbell River to Victoria, is significantly populated, much of the western part of Vancouver Island and the rest of the coast is covered by thick, tall and sometimes impenetrable temperate rainforest

7.
Canada
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Canada is a country in the northern half of North America. Canadas border with the United States is the worlds longest binational land border, the majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its territory being dominated by forest and tundra. It is highly urbanized with 82 per cent of the 35.15 million people concentrated in large and medium-sized cities, One third of the population lives in the three largest cities, Toronto, Montreal and Vancouver. Its capital is Ottawa, and other urban areas include Calgary, Edmonton, Quebec City, Winnipeg. Various aboriginal peoples had inhabited what is now Canada for thousands of years prior to European colonization. Pursuant to the British North America Act, on July 1,1867, the colonies of Canada, New Brunswick and this began an accretion of provinces and territories to the mostly self-governing Dominion to the present ten provinces and three territories forming modern Canada. With the Constitution Act 1982, Canada took over authority, removing the last remaining ties of legal dependence on the Parliament of the United Kingdom. Canada is a parliamentary democracy and a constitutional monarchy, with Queen Elizabeth II being the head of state. The country is officially bilingual at the federal level and it is one of the worlds most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Its advanced economy is the eleventh largest in the world, relying chiefly upon its abundant natural resources, Canadas long and complex relationship with the United States has had a significant impact on its economy and culture. Canada is a country and has the tenth highest nominal per capita income globally as well as the ninth highest ranking in the Human Development Index. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, Canada is an influential nation in the world, primarily due to its inclusive values, years of prosperity and stability, stable economy, and efficient military. While a variety of theories have been postulated for the origins of Canada. In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona, from the 16th to the early 18th century Canada referred to the part of New France that lay along the St. Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named The Canadas, until their union as the British Province of Canada in 1841. Upon Confederation in 1867, Canada was adopted as the name for the new country at the London Conference. The transition away from the use of Dominion was formally reflected in 1982 with the passage of the Canada Act, later that year, the name of national holiday was changed from Dominion Day to Canada Day

8.
Strike-slip tectonics
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Strike-slip tectonics is concerned with the structures formed by, and the tectonic processes associated with, zones of lateral displacement within the crust or lithosphere. In the early stages of strike-slip fault formation, displacement within basement rocks produces characteristic fault structures within the overlying cover and this will also be the case where an active strike-slip zone lies within an area of continuing sedimentation. At low levels of strain the overall simple shear causes a set of faults to form. The dominant set, known as R shears, form at about 15° to the fault with the same shear sense. The R shears are then linked by a set, the R shear that form at about 75° to the main fault trace. The somewhat oblique segments will link downwards into the fault at the base of the sequence with a helicoidal geometry. In detail many strike-slip faults at surface consist of en echelon and/or braided segments in many cases probably inherited from previously formed Riedel shears, in cross-section the displacements are dominantly reverse or normal in type depending on whether the overall fault geometry is transpressional or transtensional. As the faults tend to join downwards onto a strand in basement. Fault zones with dominantly reverse faulting are known as positive flowers, the identification of such structures, particularly where positive and negative flowers are developed on different segments of the same fault, are regarded as reliable indicators of strike-slip. Strike slip duplexes occur at the step over regions of faults and these occur between two or more large bounding faults which usually have large displacement. An idealized strike-slip fault runs in a line with a vertical dip and has only horizontal motion. In reality, as strike slip faults become large and developed, a long strike slip fault follows a staircase-like trajectory consisting of interspaced fault planes that follow the main fault direction. These sub parallel stretches are isolated by offsets at first, in long stretches of strike-slip the fault plane can start to curve, giving rise to structures similar to step overs. Right lateral motion of a slip fault at a right step over gives rise to extensional bends characterised by zones of subsidence, local normal faults. On extensional duplexes, normal faults will accommodate the vertical motion, similarly, left stepping at a dextral fault generates contractional bends, shortening the step overs which is displayed by local reverse faults, push-up zones, and folds. On contractional duplex structures, thrust faults will accommodate vertical displacement rather than being folded, strike slip dulexes are passive structures, they form as a response to displacement of the bounding fault rather than by the stresses from plate motion. Each horse has a length that varies from half to twice the spacing between the bounding fault planes, because the motion of the duplexes may be heterogeneous, the individual horses can experience a rotation with a horizontal axis, which results in the formation of scissor faults. Scissor faults exhibit normal motion at one end of the horse, an example of strike slip duplexes were observed in the Lambertville sill, New Jersey

9.
Epicenter
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The term was coined by the Irish seismologist Robert Mallet. The word, however, is misused to mean center. In seismology, the epicenter is the point on the Earths surface directly above the point where the fault begins to rupture, however, in larger events, the length of the fault rupture is much longer, and damage can be spread across the rupture zone. During an earthquake seismic waves propagate spherically out from the hypocenter, outside of the seismic shadow zone both types of wave can be detected but, due to their different velocities and paths through the Earth, they arrive at different times. This distance is called the distance, commonly measured in °. Once epicentral distances have been calculated from at least three seismographic measuring stations, it is a matter to find out where the epicenter was located using trilateration. Epicentral distance is used in calculating seismic magnitudes developed by Richter. Epicenter is frequently misused when not employed in the context of seismology and it is often utilized as an alternative to centre. For example, Travel is restricted in the Chinese province thought to be the epicentre of the SARS outbreak, garners Modern American Usage gives several examples of such misuse. However, Garner notes that these misusages may be metaphorical uses of the term to describe focal points of unstable and potentially destructive environments

10.
Vancouver Island
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Vancouver Island is in the northeastern Pacific Ocean, just off the coast of Canada. It is part of the Canadian province of British Columbia, the island is 460 kilometres in length,100 kilometres in width at its widest point, and 32,134 km2 in area. It is the largest island on the West Coast of North America and this area has one of the warmest climates in Canada, and since the mid-1990s has been mild enough in a few areas to grow subtropical Mediterranean crops such as olives and lemons. Vancouver Island has a population of 759,366 according to the Canada 2011 Census, nearly half of that figure live in the metropolitan area of Greater Victoria. Other notable cities and towns on Vancouver Island include Nanaimo, Port Alberni, Parksville, Courtenay, and Campbell River. Victoria, the city of British Columbia, is located on the island. Vancouver Island has been the homeland to many indigenous peoples for thousands of years, the island was explored by British and Spanish expeditions in the late 18th century. Quadras name was dropped from the name. It is one of several North American locations named after George Vancouver, Vancouver Island is the worlds 43rd largest island, Canadas 11th largest island, and Canadas second most populous island after the Island of Montreal. It is the largest Pacific island anywhere east of New Zealand, Vancouver Island has been the homeland to many indigenous peoples for thousands of years. The groupings, by language, are the Kwakwakawakw, Nuu-chah-nulth and their cultures are connected to the natural resources abundant in the area. The Kwakwakawakw today number about 5,500, who live in British Columbia on northern Vancouver Island and they are also known as Kwakiutl in English, from one of their tribes, but they prefer their autonym Kwakwakawakw. Their indigenous language, part of the Wakashan family, is Kwakwala, the name Kwakwakawakw means speakers of Kwakwala. The language is now spoken by less than 5% of the population—about 250 people, today 17 separate tribes make up the Kwakwakawakw. Some Kwakwakawakw groups are now extinct, Kwakwala is a Northern Wakashan language, a grouping shared with Haisla, Heiltsuk and Wuikyala. The Nuu-chah-nulth are indigenous peoples in Canada and their traditional home is on the west coast of Vancouver Island. The Nuu-chah-nulth speak a Southern Wakashan language and are related to the Makah of the Olympic Peninsula, Washington State. The Coast Salish are the largest of the southern groups and they are a loose grouping of many tribes with numerous distinct cultures and languages

11.
Washington (state)
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It was admitted to the Union as the 42nd state in 1889. Washington is sometimes referred to as Washington State or the State of Washington to distinguish it from Washington, Washington is the 18th largest state with an area of 71,362 square miles, and the 13th most populous state with over 7 million people. Washington is the second most populous state on the West Coast and in the Western United States, Mount Rainier, an active stratovolcano, is the states highest elevation at almost 14,411 feet and is the most topographically prominent mountain in the contiguous United States. Washington is a leading lumber producer and its rugged surface is rich in stands of Douglas fir, hemlock, ponderosa pine, white pine, spruce, larch, and cedar. Manufacturing industries in Washington include aircraft and missiles, shipbuilding and other equipment, lumber, food processing, metals and metal products, chemicals. Washington has over 1,000 dams, including the Grand Coulee Dam, built for a variety of purposes including irrigation, power, flood control, the Washington Territory was named after George Washington, the first President of the United States. The area was part of a region called the Columbia District after the Columbia River. The area was renamed Washington in order to avoid confusion with the District of Columbia, Washington is the only U. S. state named after a president. To distinguish it from the U. S. capital, which is named for George Washington, Washington is sometimes referred to as Washington State, or, in more formal contexts. Washingtonians and other residents of the Pacific Northwest refer to the state simply as Washington, calling the nations capital Washington, D. C. or, often, Washington is the northwestern-most state of the contiguous United States. Washington is bordered by Oregon to the south, with the Columbia River forming the western part, to the west of Washington lies the Pacific Ocean. The high mountains of the Cascade Range run north-south, bisecting the state, from the Cascade Mountains westward, Western Washington has a mostly marine west coast climate, with mild temperatures and wet winters, autumns and springs, and relatively dry summers. The Cascade Range contains several volcanoes, which reach altitudes significantly higher than the rest of the mountains, from the north to the south, these major volcanoes are Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams. Mount Rainier, the tallest mountain in the state, is 50 miles south of the city of Seattle and it is also covered with more glacial ice than any other peak in the contiguous 48 states. Western Washington also is home of the Olympic Mountains, far west on the Olympic Peninsula and these deep forests, such as the Hoh Rainforest, are among the only temperate rainforests in the continental United States. Eastern Washington – the part of the state east of the Cascades – has a dry climate. It includes large areas of steppe and a few truly arid deserts lying in the rain shadow of the Cascades. Farther east, the climate becomes less arid, with annual rainfall increasing as one goes east to 21.2 inches in Pullman, the Okanogan Highlands and the rugged Kettle River Range and Selkirk Mountains cover much of the northeastern quadrant of the state

12.
Cascadia subduction zone
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The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island to northern California. It is a long, sloping subduction zone that separates the Explorer, Juan de Fuca, and Gorda plates, on the one hand. The denser oceanic plate is subducting beneath the less dense continental plate offshore of British Columbia, Washington, Oregon, the North American Plate is moving in a southwest direction, overriding the oceanic plate. The Cascadia subduction zone is where the two plates meet, tectonic processes active in the Cascadia subduction zone region include accretion, subduction, deep earthquakes, and active volcanism of the Cascades. This volcanism has included such notable eruptions as Mount Mazama about 7,500 years ago, Mount Meager about 2,350 years ago, and Mount St. Helens in 1980. Major cities affected by a disturbance in this zone include Vancouver and Victoria, British Columbia, Seattle, Washington. In the 1960s, underground fractures were uncovered by oil companies in Puget Sound and these were believed to be inactive through the 1990s. In the 1980s, geophysicists Tom Heaton and Hiroo Kanamori of Caltech compared the generally quiet Cascadia to more active subduction zones elsewhere in the Ring of Fire, at the time of the 1700 earthquake, there were no written records of the event in Cascadia. Orally-transmitted legends from the Olympic Peninsula area talk of a battle between a thunderbird and a whale. Therefore, in a 2005 study, seismologist Ruth Ludwin set out to collect, reports from the Huu-ay-aht, Makah, Hoh, Quileute, Yurok, and Duwamish peoples referred to earthquakes and saltwater floods. This collection of data allowed her team to come up with a date range for the event. During low tide one day in March 1986, paleogeologist Brian Atwater dug along Neah Bay using a nejiri gama, underneath the top layer of sand, he uncovered a distinct plant—arrowgrass—that had grown in a layer of marsh soil. This was proof that the ground had suddenly sunk under sea level, the events had happened so quickly as to cause the top layer of sand to seal away any air, thus preserving the centuries-old plants. In 1987, Atwater mounted another expedition paddling up the Copalis River with Dr. David Yamaguchi, who was then studying the eruptions of Mount St. Helens. The pair happened upon a section of ghost forest, so-called due to the dead, originally thought to have died slowly due to a gradual rise in sea level, closer inspection yielded a different story, the land plummeted up to two meters during an earthquake. Having initially tested spruce using tree-ring dating, they found that the stumps were too rotted to count all the outer rings. However, upon having examined those of the red cedar and comparing them to the living specimens meters away from the banks. There were rings up until the year 1690, indicating that the incident had occurred shortly thereafter, root samples confirmed their conclusion, narrowing the time frame to the winter of 1699 to 1700

13.
Juan de Fuca Plate
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It is named after the explorer of the same name. One of the smallest of Earths tectonic plates, the Juan de Fuca Plate is a remnant part of the once-vast Farallon Plate, the Juan de Fuca plate system has its origins with Panthalassas oceanic basin and crust. This oceanic crust has primarily been subducted under the North American plate, Panthalassas oceanic plate remnants are understood to be the Juan de Fuca, Gorda, Cocos and the Nazca plates, all four of which were part of the Farallon Plate. The Juan de Fuca plate is bounded on the south by the Blanco Fracture Zone, on the north by the Nootka Fault and along the west by the Pacific Plate. The Juan de Fuca plate itself has since fractured into three pieces, and the name is applied to the plate in some references. The three fragments are differentiated as such, the piece to the south is known as the Gorda Plate, the separate pieces are demarcated by the large offsets of the undersea spreading zone. These in turn are part of the Pacific Ring of Fire, the last megathrust earthquake at the Cascadia subduction zone was the 1700 Cascadia earthquake, estimated to have a moment magnitude of 8.7 to 9.2. Based on carbon dating of tsunami deposits, it occurred around 1700. As reported in National Geographic on 8 December 2003, Japanese records indicate the quake caused a tsunami in Japan, in 2008, small earthquakes were observed within the plate. The unusual quakes were described as more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport. The quakes were unlike most quakes in that they did not follow the pattern of a quake, followed by smaller aftershocks, rather. Furthermore, they did not occur on the plate boundary. The subterranean quakes were heard on hydrophones, and scientists described the sounds as similar to thunder, the basaltic formations of this plate could potentially be suitable for long-term CO2 sequestration as part of a carbon capture and storage system. Injection of CO2 would lead to the formation of stable carbonates and it is estimated that 100 years of US carbon emissions could be stored securely, without risk of leakage back into the atmosphere. Geology of the Pacific Northwest Plate tectonics National Geographic on Japanese records verifying an American earthquake Cascadia tectonic history with map

14.
Explorer Plate
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The Explorer Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada. The eastern boundary of the Explorer Plate is being subducted under the North American Plate. The southern boundary is a collection of transform faults, the Sovanco Fracture Zone, to the southeast is another transform boundary, the Nootka Fault separating it from the Juan de Fuca Plate. To the northwest is a divergent boundary with the Pacific Plate forming the Explorer Ridge, the Explorer Plate is the northernmost remnant of the Farallon Plate. Geology of the Pacific Northwest Cascadia tectonic history

15.
North American Plate
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The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Russia, and parts of Iceland and the Azores. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia, the plate includes both continental and oceanic crust. The interior of the continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of material called terranes. It is thought that much of North America west of the Rocky Mountains is composed of such terranes, the parallel Septentrional and Enriquillo-Plantain Garden faults, which run through the island of Hispaniola and bound the Gonâve Microplate, are also a part of the boundary. On the northerly boundary is a continuation of the Mid-Atlantic ridge called the Gakkel Ridge, the rest of the boundary in the far northwestern part of the plate extends into Siberia. On its western edge, the Farallon Plate has been subducting under the North American Plate since the Jurassic Period, the Juan de Fuca, Explorer, Gorda, Rivera, Cocos and Nazca plates are remnants of the Farallon Plate. The boundary along the Gulf of California is complex and it is generally accepted that a piece of the North American Plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. A few hotspots are thought to exist below the North American Plate, the most notable hotspots are the Yellowstone, Raton, and Anahim hotspots. The Yellowstone and Anahim hotspots are thought to have first arrived during the Miocene period and are still geologically active, for the most part, the North American Plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge. One recent study suggests that a convective current is propelling the plate. Geologic timeline of Western North America New Madrid Seismic Zone - an ancient intraplate fault zone within the North American Plate, notable as early as 1699 Notes

16.
Intraplate earthquake
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An intraplate earthquake occurs in the interior of a tectonic plate, whereas an interplate earthquake is one that occurs at a plate boundary. Interplate earthquakes, which occur at plate boundaries, are more common, nonetheless, very large intraplate earthquakes can inflict heavy damage, particularly because such areas are not accustomed to earthquakes and buildings are usually not seismically retrofitted. The surface of the Earth is made up of seven primary and eight secondary tectonic plates, the large plates move very slowly, owing to convection currents within the mantle below the crust. Because they do not all move in the direction, plates often directly collide or move laterally along each other. Relatively few earthquakes occur in environments, most occur on faults near plate margins. By definition, intraplate earthquakes do not occur near plate boundaries, compared to earthquakes near plate boundaries, intraplate earthquakes are not well understood, and the hazards associated with them may be difficult to quantify. The Charleston quake was particularly surprising because, unlike Boston and New York, in 2001, a large intraplate earthquake devastated the region of Gujarat, India. The earthquake occurred far from any plate boundaries, which meant the region above the epicenter was unprepared for earthquakes, in particular, the Kutch district suffered tremendous damage, where the death toll was over 12,000 and the total death toll was higher than 20,000. The 1888 earthquake in Río de la Plata, Brazil, was also an intraplate quake, many cities live with the seismic risk of a rare, large intraplate earthquake. The cause of earthquakes is often uncertain. In many cases, the fault is deeply buried. Under these circumstances it is difficult to calculate the exact seismic hazard for a given city, some progress is being made in understanding the fault mechanics driving these earthquakes. Scientists continue to search for the causes of earthquakes. The best success has come with detailed micro-seismic monitoring, involving dense arrays of seismometers, in this manner, very small earthquakes associated with a causative fault can be located with great accuracy, and in most cases these line up in patterns consistent with faulting. Cryoseisms can sometimes be mistaken for intraplate earthquakes, New Madrid Seismic Zone Saint Lawrence rift system Stein, S. and S. Mazzotti. Continental Intraplate Earthquakes, Science and Policy Issues, Geological Society of America, Special Paper 425

17.
1946 Vancouver Island earthquake
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The 1946 Vancouver Island earthquake occurred with a moment magnitude of 7.3 that struck Vancouver Island, on the Coast of British Columbia, Canada, at 10,15 a. m. on June 23. The main shock occurred in the Forbidden Plateau area northwest of Courtenay. While most of the earthquakes in the Vancouver area occur at tectonic plate boundaries. Shaking was felt from Portland, Oregon to Prince Rupert, British Columbia and this earthquake is Canadas largest historic onshore earthquake.1 on the moment magnitude scale. The tectonics that caused the 1946 Vancouver Island earthquake are poorly known, no surface expression of the offset was noticed, most likely because the epicentre area is very remote and densely forested. The estimated depth of the places it within the continental crust, not at the margin with the Cascadia subduction zone. Specifically, the epicentre was positioned somewhere in the Forbidden Plateau region. Though very destructive, the earthquake caused two deaths, Jacob L. Kingston, aged 69, and Daniel Fidler, who was 50. Kingston suffered an attack, while Fidler drowned when his dinghy was swamped by a wave. In Vancouver, damage consisted of lofty buildings oscillating violently, in addition, within the city, at least one gas line cracked and several power outages occurred. Fires broke out in several chimneys, and at least one bridge was fractured by the shaking. In the Hotel Vancouver, which housed the elderly and caught on fire, more than 500 war veterans families fled the flames. One writer, George Finley, stated that the Lions Gate Bridge swayed like a leaf, coinciding with a low, rumbling sound, some chimneys were fractured in Victoria, and people in Victoria and Vancouver experienced great fright, with some seen fleeing into the streets. Landslides created by the earthquake were common throughout Vancouver Island, land subsidence resulted from the earthquake, most commonly around shorelines on the Strait of Georgia. This included the bottom of Deep Bay which sank between 2.7 m and 25.6 m and these measurements were reported by the Canadian Hydrographic Service. Also, a 3-metre ground shift occurred on Read Island, ships throughout the region were affected, and those on board them during the earthquake described it as similar to having run over a sand bar or striking a rock. Undersea power lines were destroyed in the long narrow Alberni Inlet, all lighthouse keepers in the surrounding area felt the earthquake, and experienced damage including shattered windows and smashed dishes. A tsunami struck the west coast of Texada Island with two waves, the first being 2 metres high and the second 1 metre high, the earthquake caused a landslide near Mount Colonel Foster

18.
Natural Resources Canada
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It was created in 1995 by amalgamating the now-defunct Departments of Energy, Mines and Resources and Forestry. Natural Resources Canada works to ensure the development of Canadas natural resources, including energy, forests. NRCan also uses its expertise in earth sciences to build and maintain a knowledge base of our landmass. To promote internal collaboration, NRCan has implemented a departmental wide wiki based on MediaWiki, under the Canadian constitution, responsibility for natural resources belongs to the provinces, not the federal government. However, the government has jurisdiction over off-shore resources, trade and commerce in natural resources, statistics, international relations. The current Minister of Natural Resources is Jim Carr as of November 4,2015, the department is governed by the Resources and Technical Surveys Act, R. S. C. C. R-7 and the Department of Natural Resources Act, S. C, structured along business lines according to types of natural resources and areas of interest

19.
Seismological Society of America
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The Seismological Society of America is an international scientific society devoted to the advancement of seismology and the understanding of earthquakes for the benefit of society. Founded in 1906, the society has members throughout the world representing seismologists and other geophysicists, geologists, engineers, insurers, the society hosts an annual meeting every April. The meeting is open to anyone, SSA members receive a discount on their meeting registration. The Eastern Section of SSA hosts a meeting each fall. American Geological Institute Geological Society of America IRIS Consortium List of geoscience organizations Sources SSA official website

20.
1700 Cascadia earthquake
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The 1700 Cascadia earthquake occurred along the Cascadia subduction zone on January 26 with an estimated moment magnitude of 8. 7–9.2. The length of the rupture was about 1,000 kilometers with an average slip of 20 meters. The earthquake caused a tsunami struck the coast of Japan, and may also be linked to the Bonneville Slide. It is suggested that the 1700 earthquake took place at about 21,00 on January 26,1700, the Japanese records exist primarily in the prefecture of Iwate, in communities such as Tsugaruishi, Kuwagasaki and Ōtsuchi. This includes both inland stands of trees, such as one on the Copalis River in Washington, and pockets of tree stumps that are now under the ocean surface, sediment layers in these locations demonstrate a pattern consistent with seismic and tsunami events occurring around this time. Core samples from the floor, as well as debris samples from some earthquake-induced landslides in the Pacific Northwest. Archaeological research in the region has uncovered evidence of coastal villages having been flooded and abandoned around 1700. Local Native American and First Nations groups residing in Cascadia did not have a tradition of record-keeping. However, numerous oral traditions describing a great earthquake and tsunami-like flooding exist among indigenous peoples from British Columbia to Northern California. Masit was the community on Pachina Bay not to have been wiped out. Makah stories from Washington speak of a great earthquake, of which the only survivors were those who fled inland before the tsunami hit. The Quileute people in Washington have a story about a flood so powerful that villagers in their canoes were swept all the way to the Hood Canal. The geological record reveals that great earthquakes occur in the Cascadia subduction zone about every 500 years on average, there is evidence of at least 13 events at intervals from about 300 to 900 years with an average of 570–590 years. Previous earthquakes are estimated to have occurred in 1310 AD,810 AD,400 AD,170 BC and 600 BC. These cities do have many structures, especially bridges and unreinforced brick buildings, consequently. Recent findings conclude that the Cascadia subduction zone is more complex, geologists have also determined the Pacific Northwest is not prepared for such a colossal quake. The tsunami produced could reach heights of 80 to 100 feet, a 2004 study revealed the potential for relative mean sea level rise along the Cascadia subduction zone. It postulated that cities on the west coast of Vancouver Island, such as Tofino and Ucluelet, are at risk for a 1–2 m subsidence, some other subduction zones have such earthquakes every 100 to 200 years, the longer interval results from slower plate motions

21.
1929 Grand Banks earthquake
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The 1929 Grand Banks earthquake occurred on November 18. The shock had a moment magnitude of 7.2 and a maximum Rossi–Forel intensity of VI and was centered in the Atlantic Ocean off the south coast of Newfoundland in the Laurentian Slope Seismic Zone. The earthquake was centred on the edge of the Grand Banks of Newfoundland and it was felt as far away as New York City and Montreal. The quake, along two faults 250 kilometres south of the Burin Peninsula, triggered a large submarine landslide displacing and it snapped 12 submarine transatlantic telegraph cables and led to a tsunami that arrived in three waves. Newfoundland, Canada and Saint Pierre and Miquelon had the largest impact and this was Canadas largest submarine landslide ever recorded, up to 500 times the size of 1894 Saint-Alban subaerial slide. In 2002 Natural Resources Canada and the United States Geological Survey, the tsunami waves had an amplitude of 3–8 metres, and a runup of 13 metres along the Burin Peninsula. It destroyed many south coastal communities on the Peninsula, killing 27 or 28 people, all means of communication were cut off by the destruction, and relief efforts were further hampered by a blizzard that struck the day after. This was Canadas largest submarine landslide ever recorded, up to 500 times the size of 1894 Saint-Alban landslide, tsunami travel times demonstrate the strong anisotropy of the propagating waves. The waves reach open ocean islands such as Bermuda in about 2 h and the Azores in about 4 h. At the same time, tsunami wave speeds are slower in the direction of the North America coast. Prince Edward Island had felt the earthquake the intensity was rated at the time IV - VI on the Rossi-Forel scale, in PEI it ranged from an intensity of a III - V. On the French islands of Saint Pierre and Miquelon, about 18 kilometres west of the Burin Peninsula, people were woken around 16, at 17,20, the tsunami reached the island of Saint-Pierre, submerging the docks. The worst damage was reported on the then named Île-aux-Chiens. The tsunami hit from the south, rising above the height of the bank that protects the south coast. It damaged and moved some of the houses, there were no reported injuries or casualties from the islands, donations from across Newfoundland, Canada, the United States and United Kingdom totaled $250,000. There was never an official list of the victims produced by any branch of the Newfoundland government. In the report entitled Loss of Life, the Honourable Dr. Harris Munden Mosdell, Chairman of the Board of Health Burin West, reported, twenty-five deaths were due directly to the upheaval. Two other deaths occurred subsequently and were due to shock and exposure, one sand layer, thought to be deposited by the 1929 tsunami, at Taylors Bay was found 13 centimetres below the turf line

22.
1933 Baffin Bay earthquake
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The 1933 Baffin Bay earthquake struck Greenland and the Northwest Territories, Canada with a moment magnitude of 7.7 at 18,21,35 Eastern Time Zone on November 20. The main shock epicenter was located in Baffin Bay on the east coast of Baffin Island, shaking was only felt at the small town of Upernavik, Greenland. The event is the largest to strike the passive margin of North America and is the largest north of the Arctic Circle, no damage was reported because of its offshore location and the small population of the nearby onshore communities. List of earthquakes in 1933 List of earthquakes in Canada Sources

23.
1985 Nahanni earthquakes
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The 1985 Nahanni earthquakes is the name for a continuous sequence of earthquakes that began in 1985 in the Nahanni region of the Northwest Territories, Canada. The largest of these occurred on December 23, reaching 6.9 on the moment magnitude scale. This is one of the most significant earthquakes in Canada during the 20th century, the earthquakes had a long succession of aftershocks and jolts. The earthquakes amazed both the public and the earth science community and have been felt in the Yukon, Alberta, Saskatchewan, British Columbia. List of earthquakes in Canada Sources

24.
2000 Kipawa earthquake
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The 2000 Kipawa earthquake struck Quebec and Ontario, Canada with a moment magnitude of 5.2 at 6,22 a. m. on January 1. It occurred in the Western Quebec Seismic Zone, the main shock epicenter was located in Lake Kipawa about 10 km north of Témiscaming in southwestern Quebec and 70 km northeast of North Bay, Ontario. The shaking associated with this earthquake was strongest within 50 km of the epicenter and it was felt in Témiscaming, North Bay and as far away as Toronto, making it one of the most significant earthquakes in Canada in 2000. The earthquake was triggered by major thrust faults associated with the Ottawa-Bonnechere Graben, minor damage was reported during this earthquake, including fallen light objects, a damaged ventilation pipe and fractures in plaster. The earthquakes epicenter was close to the epicenter of the 1935 Timiskaming earthquake. A total of 17 aftershocks were recorded, List of earthquakes in 2000 List of earthquakes in Canada

25.
2001 Nisqually earthquake
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The 2001 Nisqually earthquake occurred at 10,54,32 local time on February 28. The intraslab earthquake had a moment magnitude of 6.8, the epicenter was in the southern Puget Sound, northeast of Olympia, but the shock was felt in Oregon, Canada, eastern Washington, and Idaho. This was one of large earthquakes that occurred in the Puget sound region in the prior 52 years. One person died of an attack and several hundred were injured. Similar significant earthquakes occurred in the general region on April 29,1965. Although there were no directly-related deaths, local outlets reported that there was one death from a heart attack. Most of the property damage occurred very near the epicenter or in unreinforced concrete or masonry buildings, such as those in the First Hill, Pioneer Square, the Trinity Parish Church on First Hill was severely damaged. The air traffic control tower at Sea–Tac Airport was heavily damaged, the quake splintered a buttress under the dome of the capitol building in Olympia, but previous earthquake-resistance work prevented more serious harm to the building. Additionally, power outages affected downtown Seattle, the U. S. Militarys Ft. Lewis and McChord Air Force Base received damage and there was very slight damage in Victoria, British Columbia. Following the quake, many buildings and structures in the area were closed temporarily for inspection and this included several bridges, all state offices in Olympia, and Boeings factories in the Seattle area. Various schools in the also closed for the day. The Fourth Avenue Bridge in downtown Olympia was heavily damaged and was torn down. In Seattle, the Alaskan Way Viaduct and its seawall were damaged, forcing the viaduct to close for emergency repairs, approximately $305 million of insured losses and a total of $2 billion worth of damage was caused in the state of Washington. The area was declared a disaster area by president George W. Bush and was therefore able to receive federal recovery assistance. The number of businesses in the affected region was relatively small. At least 20% of businesses surrounding the heavily affected area took direct losses, none of these businesses received money for direct damage from federal aid or insurance. Many businesses did not receive any aid at all and those that did receive aid had no help with indirect losses. Indirect losses varied from inventory or data corruption, disruption in the workplace, productivity, data and inventory losses were possibly the most damaging, especially for retail stores

26.
2010 Central Canada earthquake
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The 2010 Central Canada earthquake occurred with a moment magnitude of 5.0 in Central Canada on 23 June at about 13,41,41 EDT and lasted about 30 seconds. The epicentre was situated in the area of Buckingham, Quebec, approximately 56 kilometres north of Ottawa, Ontario, closest to the settlement of Val-des-Bois, canadas capital, Ottawa, declared this earthquake as being its most powerful in 65 years. It was the first moderate earthquake associated with the Western Quebec Seismic Zone since 20 April 2002, southern Ontario was also affected by the 1998 magnitude 5.2 Mw Pymatuning earthquake, associated with a different seismic region. Although a 5.0 magnitude quake is considered to be moderate. The magnitude 5.0 Mw intraplate earthquake occurred near the edge of the Western Quebec Seismic Zone, known for frequent. The processes causing the earthquakes in the zone are not well understood, the initial focal mechanism of the 2010 earthquake suggests reverse faulting on a fault trending southeast-northwest. However, the size and depth of this make it uncertain whether the causative fault can be identified. Earthquakes of magnitude 4.5 or greater are fairly infrequent in the area, some studies suggest, however, that larger earthquakes of magnitude around 7 may have occurred 4550 and 7060 years BP. The Globe and Mail reported that Twitter users as distant as Springfield, Massachusetts, Traverse City, Michigan, the blogosphere and other social media sites like Facebook were swamped by posts referring to the 2010 Ottawa earthquake or the 2010 Toronto earthquake. Places all the way southward to New Jersey reported a disruptive tremor and this earthquake occurred as Canadian environment minister Jim Prentice was conducting an interview in Ottawa, and he reported that his chair started to move. The offices of The Globe and Mail were evacuated soon after the tremor, several media outlets also aired video of a press conference by New Democratic Party Member of Parliament Don Davies being disrupted by the quake. Part of Quebec Route 307 was closed due to a bridge collapse near Bowman that injured a nearby fisherman. Near the epicentre, many of the networks were out. The Ottawa-Carleton District School Board evacuated most of its schools, in Gracefield, Quebec, a state of emergency was declared after several buildings were damaged, including the church, some of the citys administration buildings and a hotel. In the Outaouais, about 1,300 homes lost power, immediately after the quake, cell phone service in Ottawa was down, possibly overloaded by callers. Several windows in Ottawa City Hall shattered, and a chimney in a solicitors office collapsed. Office buildings in Ottawa and Toronto were evacuated, and cracks appeared in the Parliamentary Press Gallery building on Parliament Hill, no serious damage or injuries were reported. In Toronto, Toronto Transit Commission and GO Transit service was uninterrupted and it was felt in places including Ottawa, Montreal and St. Albans, VT

27.
2012 Haida Gwaii earthquake
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The 2012 Haida Gwaii earthquake occurred just after 8,04 p. m. PDT on October 27. The shock had a moment magnitude of 7.8 and a maximum Mercalli Intensity of V, the earthquakes epicentre was on Moresby Island of the Haida Gwaii archipelago. This was the second largest Canadian earthquake ever recorded by a seismometer, after the 1949 Queen Charlotte Islands earthquake, strong shaking was felt throughout Haida Gwaii where residents in Masset, Skidegate, Sandspit, and Queen Charlotte City were evacuated to higher ground. Minor shaking was felt in Prince Rupert and in cities of the Interior such as Prince George, Quesnel. Electricity service was interrupted in Bella Coola, the 2012 quake exhibited a thrust mechanism, more characteristic of the Cascadia Subduction Zone to the south. A tsunami warning was issued for the North American Coast from the Alaskan Panhandle to Vancouver Island, Canadian authorities were questioned for issuing a tsunami warning nearly 40 minutes after the U. S. had issued their warning. The greatest wave heights recorded at tide gauges in Canada were 0. 25m at Langara Island and 0. 22m at Winter Harbour, in Tofino on Vancouver Island, the tsunami warning sirens were activated and residents in low-lying areas evacuated their homes. The maximum wave height recorded in Tofino was 0. 09m, tofinos tsunami warning system was activated after communication with the provincial coordinating centre was cut off. In the U. S. Hawaii was also placed on alert, the maximum wave height recorded at tide gauges in Hawaii was 0. 79m. Other warnings were issued for the states of Oregon and California, despite the earthquakes large magnitude, no major structural damage was reported from any of the population centres in the vicinity. This can be explained by the remoteness of the tremors epicentre, no casualties or major injuries were recorded from the quake, likely due to the sparsely populated nature of the region. As a result of the earthquake and its aftershocks, the hot springs in Gwaii Haanas National Park on Hotspring Island dried up. There were 94 aftershocks of magnitude 4.0 or greater lasting until November 7, the largest of these numerous aftershocks was a 6.3 magnitude earthquake that occurred 56 kilometres to the west of the main tremor on the morning of October 28. This was followed on October 29 by a 6.2 aftershock 50 kilometres to the south of the original quake

Normal fault in the Bozeman Group near the Harrison Reservoir, Montana

A fault in Morocco.The fault plane is the steeply leftward-dipping line in the centre of the photo, which is the plane along which the rock layers to the left have slipped downwards, relative to the layers to the right of the fault.